I have a 4100 that was ran hard before I got it. The issues I've had:
- charging system would not work --as I recall there was a relay that I plugged/unplugged 10x to fix what must have been a connector corrosion issue
- front wheel bearing (2 balls) disintegrated -- somewhere here I posted a detailed repair. I used to mow with the FEL on which required 4WD to work. Now I take the FEL off, get MUCH better rear traction, and do not need 4WD. Maybe that will avert future front wheel bearing issues. Years back I recall the dealer saying the front wheels were a weak spot
- mine burns oil -- probably a result of a water pump failure I tracked down via JD with the previous owner. I check the gas and fill the oil.
- occasionally there is no power to the starter - turn the switch and nothing. I used to think it was because of some bad sensors on the H-N-L shifter as it needs to be in N. Recently it seemed to be a wire over near the alternator. No idea really, but jiggling that wire did "fix" the problem once.
- hard to start in cold -- but see my note about burns oil; pretty sure that's related, although right now I also seem to have a fuel issue, but it's been -10 to 20 hear lately and I did see gelled fuel in the filter today. I cleaned it out, but not suspecting there's gelling further along.